I just improvise. I like the Foo Fighters. I also like to keep things simple so I just copy entire CDs over to my mp3 player. So I choose a CD and then do one song at an easy gear and the next at a hard gear and the next at an easier gear, etc. Within each song I might shift up or down each time a new verse begins or when the chorus begins. If a song with a slow tempo comes on I might skip it and go to the next one.